Method of field retrofitting a heat releaseable weldment for manual opening jacks

ABSTRACT

A heat releasable weldment for a mechanical opening jack used in combination with fluid powered valve actuators to release said manual opening jack in the event of fire comprising grooved inner and outer members which cooperate to form a eutectic chamber, said inner and said outer members being retained in spaced relationship with each other by horizontal and vertical restraining members in cooperation with a fusable eutectic alloy which is poured into said eutectic chamber and allowed to solidify together and a method to field retrofit said weldment to a mechanical opening jack is presented.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional of application Ser. No. 07/584,632, filed Sept. 19,1990, now U.S. Pat. No. 5,080,125.

FIELD OF THE INVENTION

This invention relates to temperature sensitive release mechanisms foruse on power actuated valves.

BACKGROUND OF THE INVENTION

Valves which have a remote actuator incorporated into its design and amanual override device, commonly referred to as a manual opening jack,to allow manual operation of the valve in the event of a power failureare well known in the art. Likewise, it is well known in the art toincorporate devices which are designed to override a manual opening jackto allow a valve so equipped to move to its normal position in the eventof fire. Examples of such devices are disclosed in U.S. Pat. Nos.4,421,134, 4,240,455, and 4,505,291. The major drawback of these designsis that the heat responsive mechanism must be incorporated into themanual opening jack at the time of manufacture. Thus, if it becomesdesirable to place a valve incorporating such features into serviceafter the valve has been installed in a conduit or pipe, it becomesnecessary to remove the pipe section involved from service and changeout the entire valve assembly.

It is also well known in the art to equip a remote valve actuator with afire or heat sensitive lockout cap which, when fitted to the actuator,locks the valve in an actuated position, and, in response to a high heatsituation such as a fire, releases the actuation mechanism to allow thevalve to move into its normal position. Examples of such lockout capsare disclosed in U.S. Pat. Nos. 3,771,540, 3,838,705, 3,842,853,3,896,835, 4,214,600, 4,245,662, and 4,271,857.

Of course, the disadvantage of such lockout caps is that valves soequipped are not operational while the cap is in place so that thefunction of such valves is limited to fire safety.

SUMMARY OF THE INVENTION

More specifically, this invention relates to a weldment which may beretrofitted in the field onto a manual opening jack designed for use incombination with a power actuated valve. The weldment forms atemperature sensitive release mechanism for said manual opening jack byincorporating into its design a eutectic material which melts at aspecific, predetermined temperature. Thus in the presence of fire orother undesirable high temperature situations, the eutectic materialmelts, or fuses, thus releasing the manual opening jack thereby allowingthe valve onto which such a manual opening jack has been incorporated tomove into its normal position in response to an applied force as, forexample, by a return spring incorporated into the valve actuationmechanism.

OBJECTS OF THE INVENTION

It is therefore an object of this invention to provide a heat sensitiverelease mechanism which can be retrofitted to a manual opening jackwhile the manual opening jack is mounted on a valve which is in service.

It is a further object of the invention to provide a fire sensitivevalve having a fluid powered valve actuator with a manual override and aheat sensitive release mechanism.

The novel features of the invention are set forth with particularity inthe claims. The invention well be best understood from the followingdescription when read in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a cross section view of the temperature sensitive releasemechanism.

FIG. 2 is a cross section view of the outer member of the temperaturesensitive release mechanism.

FIG. 3 is a cross section view of the inner member of the temperaturesensitive release mechanism.

FIG. 4 is an exploded plan view of the temperature sensitive releasemechanism.

FIG. 5 is a cross sectional view of the temperature sensitive releasemechanism installed on a manual opening jack.

FIG. 6 is a vertical cross section of the temperature sensitive releasemechanism installed on a manual opening jack taken along line 6--6.

FIG. 7A is a cross section of the valve section and lower portion of anactuator in the closed position.

FIG. 7B is a cross section of the upper portion of a fluid poweredactuator upon which a manual opening jack into which is incorporated thetemperature sensitive release mechanism which has been installed in thefire release position.

FIG. 8 is a cross section of a manual opening jack into which isincorporated the temperature sensitive release mechanism which has beeninstalled upon a fluid power operated actuator in conjunction with agate valve in the power mode closed position.

FIG. 9 is a cross section of a manual opening jack into which isincorporated the temperature sensitive release mechanism which has beeninstalled upon a fluid power operated actuator in conjunction with agate valve in the manual open position.

DETAILED DESCRIPTION OF THE INVENTION

In the description that follows, like parts are marked throughout thespecification and drawings with the same reference numerals,respectively. The drawings are not necessarily to scale and theproportions of certain parts have been exaggerated to better illustratethe details of the present invention.

Referring now to FIGS. 1 through 4, the temperature sensitive releasemechanism 10 is a weldment comprised of a cylindrical inner member 20which is prevented from spatial and rotational movement and maintainedin a spaced relationship to cylindrical outer member 30 within centralsmooth bore 301 of said cylindrical outer member 30 by horizontal spiralpins 101, 101a and vertical spiral pins 110, 110a in cooperation with afusable eutectic alloy as hereinafter described.

Inner member 20 is a cylindrically shaped member having threaded bore201 extending therethrough between the two flat faces 202, 202a thereof.The curved external surface of said internal member has two inwardlyradially stepped shoulders 205, 205a which cooperate to form externalflat groove 210 about the circumference thereof. Two diametricallyopposed vertical bore holes 215, 215a drilled parallel said threadedbore communicate between the external surface of the first flat face 202and said flat groove 210. The second flat face 202a has a recess 220concentric to said threaded bore of diameter intermediate the diameterof said threaded bore 201 and the diameter of said cylindrically shapedmember, the function of which is described below.

Outer member 30 is also a cylindrically shaped member having a smoothbore 301 of a diameter slightly larger than the maximum diameter ofinner member 20 extending therethrough between the two flat faces 302,302a. Intermediate said flat faces 302, 302a, two radially outwardlystepped shoulders 305, 305a cooperate to form an internal flat groove310 in the wall of said smooth bore. The outside surface of said outermember has pin threads T which extend from one of said flat faces 302aalong a portion of its length and two diametrically opposed horizontalbore holes 315, 315a located intermediate said threads and the other ofsaid flat faces drilled parallel to said flat faces which communicatebetween the outside surface of said outer member and said outer flatgroove 310.

Restricting means in the form of spiral pins 101, 101a, 110 and 110a arecomprised of a thin, flat rectangular pieces of metal which are rolledinto a cylinder in such fashion that the narrow ends of said rectangularpiece of metal overlap. When the resulting spiral is compressed as bysqueezing between the fingers, the amount of overlap is increased thusdecreasing the diameter of the cylinder. Likewise, when the compressiveforce is released, the cylinder springs back to its original diameter.

The temperature sensitive release mechanism is assembled by placing theinner member 20 into smooth bore 301 of outer member 30 so that saidflat faces 202, 202a of said inner member 20 are essentially parallel tosaid flat faces 302, 302a of said outer member. Spiral pins 101, 101aare fixedly inserted into horizontal bore holes 315, 315a, respectivelyand spiral pins 110, 110a are fixedly inserted into vertical bore holes215, 215a, respectively, said spiral pins cooperating with solidifiedfusable eutectic alloy to restrict said inner member from spatial androtational motion with reference to said outer member as hereinafterdescribed. Once assembled, internal flat groove 210 cooperates withexternal flat groove 310 to form eutectic chamber E which is filled withmelted fusable eutectic alloy through vertical bore holes 215, 215a andallowed to solidify. However, prior to filling eutectic chamber E withsaid fusable eutectic alloy, inner member 20 is arranged in spacedrelationship to outer member 30 so as to form interstitial space 120between the outer circumference of inner member 20 and the circumferenceof smooth bore 301. Said interstitial space is maintained in theassembled device by the solidified fusable eutectic alloy and functionsas a drain hole to allow the melted fusable eutectic alloy to flow outof said eutectic chamber in the event of fire or other undesirable hightemperature situation.

The fusable eutectic alloy must be chosen carefully to ensure it willmelt, or fuse, quickly in the event it is exposed to flame or hot gasseswhich might be generated in a fire. At the same time, consideration mustbe given to the normal ambient temperatures to which the alloy can beexpected to be exposed to avoid choosing an alloy with too low a meltingpoint which will fuse after prolonged exposure to the rays of the sun.Therefore, the alloy should be chosen from those alloys with narrowmelting ranges, preferably one degree Farenheit or less, and meltingpoints between approximately 275 and 300 degrees Farenheit. Typically,and by way of example and not limitation, such alloys consistessentially of 57.42- 60% Bismuth, 0-1.00% Lead, 0-42% Tin and 0-40%Cadmium. To one skilled in the art, it would also be obvious to choosean alloy with a higher melting point for use in applications where thealloy could be expected to be exposed to higher temperatures either as aresult of extreme solar heating or as a result of exposure to artificialsources of heat such as a furnace or the like. Preferably, the eutecticalloy will consist essentially of 58.00% Bismuth and 42.00% Tin and havea melting point of approximately 281° F. and a melting range of lessthan one degree Farenheit. Such an alloy is sold under the trademark"Cerrotru" by Cerro Copper & Brass Company division of CerroCorporation. One skilled in the art would recognize that alloyscomprised of other materials which exhibit the same or similar meltingcharacteristics ma be used in place of the alloy described herein.

Referring now to FIGS. 7A and 7B, gate valve 40 having flanges 401, 401afor attachment to similar mating surfaces in a pipe line or otherdevices which would employ flanges as mating surfaces, is bolted bybolts or threaded studs 405, 405a to an actuator 50, said bolts orthreaded studs being secured in threaded holes drilled in valve body 410and passing through corresponding holes 505, 505a drilled in actuatorbottom plate 501 and being secured thereto by nuts 407, 407a. Valvingmeans in the form of slab element 420 of gate assembly 42 is connectedat its upper end to the lower end of valve stem 430 which extendsthrough bonnet bore 440, located in actuator bottom plate 501, intoupper gate cavity 450. The valve stem is connected to the slab elementso that upon displacement of valve stem 430 along its longitudinal axis,the gate slab 420 is movable across flow passage 460 from a firstposition wherein the valve is closed to a second position wherein thevalve is open.

Remote controlled fluid powered valve actuators such as those intendedto be employed in combination with the invention disclosed herein arewell known in the art and typically comprise pressure responsive meanssuch as a piston, bellows or diaphragm enclosed within a pressurechamber and attached to a valve stem or valve stem extension andcooperates with said valve stem or valve stem extension to move valvingmeans contained in the valve body between a first position and a secondposition in response to the application of fluid power to said actuatorwhich is sufficient to overcome force generated by a second power sourceand further cooperating with said valve stem to return said valvingmeans to said first position in response to pressure exerted by a secondpower source, such as a return spring, against said pressure responsivemeans when said application of fluid power ceases. An indicator stem,which is aligned within a bore hole in the pressure cap of said actuatorcooperates with said pressure responsive means to reciprocally protrudefrom and retract into an enclosed position within said bore holeresponsive to movement of said valving means between said first positionand said second position.

As further shown in FIGS. 7A and 7B, remote controlled fluid poweredvalve actuator 50 has return spring 510 restrained between actuatorbottom plate 501 and the lower face 520a of primary piston 520 andenclosed within unpressurized primary exhaust chamber 580 withinpressure cylinder 590 to reciprocate said valving means upon applicationand release of fluid power to said actuator. The primary exhaust chamberis relieved of atmospheric pressure by a vent bore 600 formed throughactuator bottom plate 501. Downward opening movement of the valve stem430 is opposed by return spring 510 and is limited by engagement ofprimary piston 520 with annular face 530 of packing collar 540. By thisarrangement, travel of gate slab 420 is arrested as the slab is drivento the valve open position. Retraction movement of valve stem 430 isarrested by engagement of valve stem collar 550 with annular shoulderstop 560. Bonnet bore 440 is enlarged by counter bore 570 through whichvalve stem shoulder 550 is extended and retracted.

Primary piston 520 is threadedly coupled to valve stem 430 at threadedportion T and secured in position by nut N.

Auxiliary piston 610 is slidably coupled in sealing engagement againstthe polished cylindrical surface of indicator stem 620. Downwardmovement of auxiliary piston 610 is limited during the opening stroke bydivider plate 630 which is interposed between auxiliary exhaust chamber640 and primary pressure chamber 650. Auxiliary exhaust chamber 640 isvented to the atmosphere through bore hole 660 in the sidewall ofpressure cylinder 590 which is located immediately above divider plate630 and below radially inset shoulder 660.

Top cap 720 pressure cylinder 590 has an axially projecting shoulder 730which is threaded along its exterior and an internal bore 740 andcontains suitable packing materials 750 through which indicator stemextension 760 reciprocally extends and retracts above the top of saidshoulder in cooperation with the sliding motion of said pistons.

In operation, therefore, fluid power, either hydraulic or pneumatic isapplied through control line connection 700 to first to auxiliarypressure chamber 670 and thereafter through flow path 680 and shuttlesleeve 690 to primary pressure chamber 650. Primary piston 520 andauxiliary piston 610 both exert pressure upon valve stem 430 and thenceon gate slab 420. The stroke of auxiliary piston 610 is calculated sothat auxiliary piston 610 bottoms out on divider plate 630 after thehigh gate leasing forces and frictional drag forces have been overcome.Once auxiliary piston has bottomed out as aforesaid, valve stem 430slides out of engagement with said auxiliary piston as fluid powercontinues to be applied through flow path 680 to primary piston 520which, in turn, continues to force valve stem 430 down and gate slab 420to the full open position.

When it is desired to use the actuator to close the valve fluid powerapplied to inlet port 700 is relieved and vent 710 is opened. Aspressure contained in auxiliary pressure chamber 670 is relieved, thepressure in primary pressure chamber 650 eventually exceeds the pressurein said auxiliary pressure chamber and exerts an upward force on shuttlesleeve 690. This upward force propels auxiliary piston 610 to itsuppermost position. Fluid pressure is vented through flow paths 680 intoauxiliary pressure chamber 670 and then to the atmosphere through vent710. Return spring 510 urges both the primary piston 520 which isattached to the upper end of valve stem 430, valve stem 430 and gateslab 420 which is attached to the lower end of valve stem 430 to theupmost, or valve closed position. Indicator stem 620 and indicator stemextension 760 are likewise urged to their upmost position.

Referring now to FIG. 7B, manual opening jack 80 is threadedly connectedto said axially projecting shoulder 730 at threaded union T. Manualopening jack housing 801 is a cylindrical container which has internal,or box, threads cut in the ends of said container. Inspection ports Pare cut into the wall of the cylinder and covered by port covers C.Restrained within said housing is thrust washer assembly 90.

Thrust washer assembly 90 consists of an outer cylindrical bearingmember 901 which has an axially upwardly projecting shoulder 905 aroundits circumference and an inner cylindrical bearing member 910 having aradially inwardly stepped shoulder 915 around its lower circumferenceforming annular thrust washer retaining groove 920 which cooperates withouter bearing member 901 to retain a thrust washer, not shown.

Thrust washer assembly 90 is inserted into smooth longitudinal bore 805of housing 801. Said axially upwardly projecting shoulder 905 cooperateswith the inner wall of bore 805 to slidingly retain thrust washerassembly 90 in a perpendicular relationship with respect to thelongitudinal axis of said bore and in contact with the upper exposed end761 of indicator stem extension 760.

Prior to threadedly attaching fusible link weldment 10 to opening jackhousing 801, threaded opening jack stem 930 described below isthreadedly inserted into threaded bore 201 of internal member 20.Thereafter fusible link weldment 10 is threadedly attached to openingjack housing at its upper end forming threaded union T. As shown in FIG.5, said fusable link element can be optionally secured against rotationin said opening jack housing by the use of set screws S.

Threaded opening jack stem 930 has an enlarged circular presser foot 931formed on its lower end, said presser foot being of slightly smallerdiameter than recess 220 of inner member 20 so that when opening jackstem 930 is in its fully withdrawn position, said presser foot 931 fitsinto said recess 220 to prevent inadvertant total removal of openingjack stem 930 from opening jack assembly 90. Near the upper end ofopening jack stem 930 is an unthreaded portion upon which flats havebeen formed to engage corresponding slots in hand wheel W and anadditional threaded portion at the uppermost end upon which is threadedretaining nut N.

Weldment 10 can be retrofitted to a manual opening jack by firstremoving retaining nut N and hand wheel W. An opening jack cap, whichnormally occupies the position occupied by weldment 10 is thenthreadedly removed, after which threaded opening jack stem 930 isremoved from said opening jack cap. Opening jack stem 930 is thenthreaded into threaded opening 220 of inner member 201 of the assembledfusible weldment 10 and the resulting assembly is then threadedlyattached to opening jack housing 801. Hand wheel W is then fitted to theflats in the upper end of said threaded opening jack stem and held inplace by retaining nut N.

As shown in FIG. 8, in normal, powered, operation, threaded opening jackstem 930 is maintained in its most outward position so that presser foot931 is in contacting engagement with recess 220 of inner member 20. Inthis position, actuator stem extension 760, in cooperation with actuatorstem 430 is free to reciprocate within the actuator housing opening andclosing valve 50 in response to the application of fluid power throughported connection 700 an the venting of said fluid power through vent710. When the opening jack stem 930 is fully withdrawn, thrust washerassembly 90 which is in contacting engagement with upper end 761 ofvalve stem extension 760 slides reciprocally within said longitudinalbore 805 of housing 801 in response to pressure applied by indicatorstem extension 760.

As shown in FIG. 9, in the event of the failure of fluid power the valveactuator is urged from a first position to a second position by returnspring 510. It is possible to move the valve from said second positionto said first position, as from open to closed by turning hand wheel Wthereby advancing threaded opening jack stem 930 into the bore ofopening jack housing 801 and into contacting engagement with innermember 905 of thrust washer assembly 90. As pressure upon thrust bearingassembly 90, indicator stem extension 760 and valve stem 430 isincreased as a result of the force exerted by opening jack stem 930against the resistance of return spring 510, frictional resistance tocircular movement of opening jack stem 930 by stem extension 760 isdissipated in the thrust washer assembly thereby allowing movement ofthe gate assembly from the normally closed position of the gate slab tothe open position.

As shown in FIG. 7B, in the event of fire, the fusable eutectic alloycontained in eutectic chamber E quickly fuses and drains from weldment10 through interstitial space 120 thereby permitting inner member 20 tomove freely within assembly 10 in response to pressure exerted by returnspring 510. As pressure exerted by return spring 510 is transmitted tothreaded opening jack stem 930 through indicator stem 620 in cooperationwith indicator stem extension 760 and thrust washer assembly 90, innermember 20 is forced out of engagement with outer member 30. Inner member20 which is in threaded engagement with opening jack stem 930 is urgedout of opening jack housing 801. Also in response to said pressureexerted by said return spring 510 valve stem 430 and gate slab assembly42 are pulled into the normally closed position with flow passage 460being occluded by slab element 420.

Although the invention has been depicted in combination with a dualpiston valve actuator operated by the application of fluid power, itwill be readily understood by on skilled in the art that a manualopening jack incorporating the invention is also intended to be ofutility in conjunction with any valve actuator mechanism whichincorporates a valve stem or an indicator stem which extends from theactuator body and a return spring to supply motive force to move thevalving member of said valve from an actuated position to a normalposition.

This invention has been described with reference to an exemplaryembodiment, however, the foregoing description is not intended to beconstrued in a limiting sense. Various modifications of the disclosedembodiment as well as alternative applications of the invention will besuggested to persons skilled in the art by the foregoing specificationand illustrations. It is therefore contemplated that the appended claimswill cover any such modifications, applications or embodiments as fallwithin the true scope of the invention.

What is claimed is:
 1. The method for field retrofitting a heatreleasable weldment into a manual opening jack having a subassemblycomprising a threaded opening jack stem threaded into a retaining collarwith a hand wheel mounted thereon, said subassembly being releasablymounted in a housing consisting of:a. removing said subassembly fromsaid housing; b. removing said hand wheel from said threaded openingjack stem; c. removing said threaded opening jack stem from saidretaining collar; d. threadedly inserting said threaded opening jackstem into the threaded bore of said heat releasable weldment; e.threadedly inserting said heat releasable weldment into said housing ofsaid manual opening jack; f. reattaching said hand wheel to saidthreaded opening jack stem; and g. replacing said subassembly in saidhousing.